Blind scheduling apparatus and method in a mobile communication system

ABSTRACT

A system and a method minimize power consumption, signalling overhead, and processing load in blind scheduling in a mobile communication system. A User Equipment (UE) detects a type of an uplink (UL) grant while it is periodically allocated the UL grant. If there is no data to transmit using the UL grant, the UE determines whether to transmit a padding Medium Access Control (MAC) Protocol Data Unit (PDU) to an Evolved Universal Terrestrial Radio Access Network (E-UTRAN) Node B (eNB) using the UL grant according to the type of the UL grant.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/259,951 filed on Jan. 28, 2019, which is a continuation of Ser. No.15/194,378 filed on Jun. 27, 2016, now U.S. Pat. No. 10,194,458 issuedon Jan. 29, 2019, which is a continuation of U.S. patent applicationSer. No. 13/165,202 filed on Jun. 21, 2011, now U.S. Pat. No. 9,414,403issued on Aug. 9, 2016, which claims priority to Korean PatentApplication No. 10-2010-0058717 filed on Jun. 21, 2010, the disclosuresof which are herein incorporated by reference in their entirety.

BACKGROUND 1. Field

The present invention relates to a blind scheduling apparatus and methodin a mobile communication system.

2. Description of Related Art

Next-generation communication systems have evolved to provide a varietyof high-speed, high-capacity services to User Equipment's (UEs). LongTerm Evolution (LTE) communication system, an example of thenext-generation communication systems, uses various resource allocationschemes, one of which is blind scheduling.

The blind scheduling is a scheme in which an Evolved UniversalTerrestrial Radio Access Network (E-UTRAN) Node B (eNB) periodicallyallocates a dedicated uplink (UL) resource without prior informationabout the amount of data that a UE will transmit over an UL. The LTEcommunication system considers using blind scheduling for latencyreduction. The amount of data that a UE will transmit over a UL may bedetected using the buffer status. For convenience, a dedicated ULresource that is periodically allocated to a UE using blind schedulingwill be referred to herein as a ‘UL grant’.

When employing blind scheduling, an eNB continuously allocates adedicated UL resource or a UL grant to a UE for a relatively longperiod. So, the UE is continuously allocated the UL grant by the eNBsuch that, even when the UE has no data, it will actually transmit on aUL.

Semi-Persistent Scheduling (SPS) is one of the blind scheduling schemes.When using SPS, an eNB periodically allocates a UL grant to a UE towhich an SPS Cell Radio Network Temporary Identifier (C-RNTI) has beenallocated. The eNB may inform the UE of a UL grant allocation periodusing an SPS configuration Information Element (IE). The UE may transmitdata to the eNB using the periodically allocated UL grant. Therefore,the UE may skip the UL resource allocation process that it shouldperform with the eNB to be allocated a UL resource, contributing to areduction in the latency.

When the LTE communication system uses SPS, the latency may be reduceddue to the possible skip of the UL resource allocation process. However,a UE should transmit padding Medium Access Control (MAC) Protocol DataUnits (PDUs) using a UL grant even when it has no data to transmit on aUL, which may cause a waste of the UE battery and lead to signalingoverhead caused by the transmission of the padding MAC PDUs. Inaddition, the eNB unnecessarily decodes the padding MAC PDUs, causing apadding MAC PDU decoding processing load.

SUMMARY

To address the above-discussed deficiencies of the prior art, it is aprimary object to provide a blind scheduling apparatus and method in amobile communication system.

Another aspect of the present invention is to provide a blind schedulingapparatus and method for minimizing a waste of a UE battery caused bythe transmission of padding MAC PDUs in a mobile communication system.

Another aspect of the present invention is to provide a blind schedulingapparatus and method for minimizing a signaling overhead caused by thetransmission of padding MAC PDUs in a mobile communication system.

Yet another aspect of the present invention is to provide a blindscheduling apparatus and method for minimizing a processing load causedby the decoding of padding MAC PDUs in a mobile communication system.

In accordance with one aspect of the present invention, there isprovided a blind scheduling method of a User Equipment (UE) in a mobilecommunication system. The blind scheduling method includes detecting atype of an uplink (UL) grant, while the UE is periodically allocated aUL grant. When there is no data to transmit using the UL grant, whetherto transmit a padding Medium Access Control (MAC) Protocol Data Unit(PDU) to an Evolved Universal Terrestrial Radio Access Network (E-UTRAN)Node B (eNB) using the UL grant according to the type of the UL grant isdetermined.

In accordance with another aspect of the present invention, there isprovided a blind scheduling method of an Evolved Universal TerrestrialRadio Access Network (E-UTRAN) Node B (eNB) in a mobile communicationsystem. The blind scheduling method includes determining whether data isdetected from an Explicit uplink (UL) grant that the eNB allocates to aUser Equipment (UE). A new Explicit UL grant is allocated to the UE whenno data is detected from the Explicit UL grant. And when data isdetected from the Explicit UL grant, Hybrid Automatic RetransmissionRequest (HARQ) feedback information is transmitted to the UE accordingto a success/failure in decoding the data. The Explicit UL grant is a ULgrant that serves as resource allocation information received from theeNB over a Physical Downlink Control Channel (PDCCH) without separateconfiguration, among UL grants which are allocated after being mapped toa Cell Radio Network Temporary Identifier (C-RNTI).

In accordance with another aspect of the present invention, there isprovided a blind scheduling method of an Evolved Universal TerrestrialRadio Access Network (E-UTRAN) Node B (eNB) in a mobile communicationsystem. The blind scheduling method includes determining whether data isdetected from a Fast Access Scheduling (FAS) grant that the eNBallocates to a User Equipment (UE). A new FAS grant is allocated to theUE when no data is detected from the FAS grant. And when data isdetected from the FAS grant, Hybrid Automatic Retransmission Request(HARD) feedback information is transmitted to the UE according to asuccess/failure in decoding the data. The FAS grant is an uplink (UL)grant that is allocated after being mapped to a FAS Cell Radio NetworkTemporary Identifier (C-RNTI). The FAS C-RNTI is a C-RNTI that isallocated to a UE to allow the UE to not transmit a padding MAC PDUusing the FAS grant.

In accordance with another aspect of the present invention, there isprovided a blind scheduling method of a user equipment (UE) in a mobilecommunication system. The blind scheduling method includes determiningwhether there is data to transmit using an uplink (UL) grant, while theUE is periodically allocated the UL grant. And when there is no data totransmit using the UL grant, no padding Medium Access Control (MAC)Protocol Data Unit (PDU) is transmitted to an Evolved UniversalTerrestrial Radio Access Network (E-UTRAN) Node B (eNB) using the ULgrant.

In accordance with another aspect of the present invention, there isprovided a blind scheduling method of an Evolved Universal TerrestrialRadio Access Network (E-UTRAN) Node B (eNB) in a mobile communicationsystem. The blind scheduling method includes allocating an uplink (UL)grant to a user equipment (UE) using Semi-Persistent Scheduling (SPS).And when no data is detected from the UL grant, it is determined thatthe UE transmits no data using the UL grant.

In accordance with another aspect of the present invention, there isprovided a user equipment (UE) for a mobile communication system. The UEincludes a control unit detects a type of an uplink (UL) grant while theUE is periodically allocated a UL grant. And when there is no data totransmit using the UL grant, the UE determines whether to allow atransmission unit to transmit a padding Medium Access Control (MAC)Protocol Data Unit (PDU) to an Evolved Universal Terrestrial RadioAccess Network (E-UTRAN) Node B (eNB) using the UL grant according tothe type of the UL grant.

In accordance with another aspect of the present invention, there isprovided an Evolved Universal Terrestrial Radio Access Network (E-UTRAN)Node B (eNB) for a mobile communication system. The eNB includes aresource allocation unit that allocates an Explicit Uplink (UL) grantunder specific control. A transmission unit transmits Hybrid AutomaticRetransmission Request (HARQ) feedback information to a user equipment(UE) under specific control. And a control unit determines whether datais detected from the Explicit UL grant, controls the resource allocationunit to allocate a new Explicit UL grant to the UE when no data isdetected from the Explicit UL grant, and controls the transmission unitto transmit HARQ feedback information to the UE according to asuccess/failure in decoding data when data is detected from the ExplicitUL grant. The Explicit UL grant is a UL grant that serves as resourceallocation information received from the eNB over a Physical DownlinkControl Channel (PDCCH) without separate configuration, among UL grantswhich are allocated after being mapped to a Cell Radio Network TemporaryIdentifier (C-RNTI).

In accordance with another aspect of the present invention, there isprovided an Evolved Universal Terrestrial Radio Access Network (E-UTRAN)Node B (eNB) for a mobile communication system. The eNB includes aresource allocation unit, a transmission unit, and a control unit. Theresource allocation unit allocates a Fast Access Scheduling (FAS) grantunder specific control. The transmission unit transmits Hybrid AutomaticRetransmission Request (HARQ) feedback information to a user equipment(UE) under specific control. And the control unit determines whetherdata is detected from the FAS grant, controls the resource allocationunit to allocate a new FAS grant to the UE when no data is detected fromthe FAS grant, and controls the transmission unit to transmit HARQfeedback information to the UE according to a success/failure indecoding data when data is detected from the FAS grant. The FAS grant isan uplink (UL) grant that is allocated after being mapped to a FAS CellRadio Network Temporary Identifier (C-RNTI), and the FAS C-RNTI is aC-RNTI that is allocated to a UE to allow the UE to not transmit apadding MAC PDU using the FAS grant.

In accordance with another aspect of the present invention, there isprovided a user equipment (UE) for a mobile communication system. The UEincludes a control unit that determines whether there is data totransmit using an uplink (UL) grant while the UE is periodicallyallocated the UL grant, and when there is no data to transmit using theUL grant, determines to allow a transmission unit to not transmit apadding Medium Access Control (MAC) Protocol Data Unit (PDU) to anEvolved Universal Terrestrial Radio Access Network (E-UTRAN) Node B(eNB) using the UL grant.

In accordance with another aspect of the present invention, there isprovided an Evolved Universal Terrestrial Radio Access Network (E-UTRAN)Node B (eNB) for a mobile communication system. The eNB includes aresource allocation unit and a control unit. The resource allocationunit allocates an uplink (UL) grant to a user equipment (UE) usingSemi-Persistent Scheduling (SPS) under specific control. And a controlunit controls the resource allocation unit to allocate the UL grant tothe UE using SPS, and when no data is detected from the UL grant,determines that the UE transmits no data using the UL grant.

Before undertaking the DETAILED DESCRIPTION OF THE INVENTION below, itmay be advantageous to set forth definitions of certain words andphrases used throughout this patent document: the terms “include” and“comprise,” as well as derivatives thereof, mean inclusion withoutlimitation; the term “or,” is inclusive, meaning and/or; the phrases“associated with” and “associated therewith,” as well as derivativesthereof, may mean to include, be included within, interconnect with,contain, be contained within, connect to or with, couple to or with, becommunicable with, cooperate with, interleave, juxtapose, be proximateto, be bound to or with, have, have a property of, or the like; and theterm “controller” means any device, system or part thereof that controlsat least one operation, such a device may be implemented in hardware,firmware or software, or some combination of at least two of the same.It should be noted that the functionality associated with any particularcontroller may be centralized or distributed, whether locally orremotely. Definitions for certain words and phrases are providedthroughout this patent document, those of ordinary skill in the artshould understand that in many, if not most instances, such definitionsapply to prior, as well as future uses of such defined words andphrases.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure and itsadvantages, reference is now made to the following description taken inconjunction with the accompanying drawings, in which like referencenumerals represent like parts:

FIG. 1 illustrates a process of a UE in an LTE communication systemusing a first blind scheduling scheme according to an embodiment of thepresent invention;

FIG. 2 is a signaling diagram of a signal exchange process between aneNB and a UE in an LTE communication system using the first blindscheduling scheme according to an embodiment of the present invention;

FIG. 3 illustrates a process of the eNB 213 in FIG. 2;

FIG. 4 illustrates a process of the UE 211 in FIG. 2;

FIG. 5 is a signaling diagram of an example process of transmitting aFAS configuration IE to a UE by an eNB in an LTE communication systemusing a third blind scheduling scheme according to an embodiment of thepresent invention;

FIG. 6 is a signaling diagram of an another example process oftransmitting a FAS configuration IE to a UE by an eNB in an LTEcommunication system using a third blind scheduling scheme according toan embodiment of the present invention;

FIG. 7 illustrates a process of a UE in an LTE communication systemusing a third blind scheduling scheme according to an embodiment of thepresent invention;

FIG. 8 is a signaling diagram of a signal exchange process between aneNB and a UE in an LTE communication system using a third blindscheduling scheme according to an embodiment of the present invention;

FIG. 9 illustrates a process of the eNB 813 in FIG. 8;

FIG. 10 illustrates a process of the UE 811 in FIG. 8;

FIG. 11 is a diagram of an internal structure of an eNB in an LTEcommunication system according to an embodiment of the presentinvention; and

FIG. 12 is a diagram of an internal structure of a UE in an LTEcommunication system according to an embodiment of the presentinvention.

Throughout the drawings, the same drawing reference numerals will beunderstood to refer to the same elements, features and structures.

DETAILED DESCRIPTION

FIGS. 1 through 12, discussed below, and the various embodiments used todescribe the principles of the present disclosure in this patentdocument are by way of illustration only and should not be construed inany way to limit the scope of the disclosure. Those skilled in the artwill understand that the principles of the present disclosure may beimplemented in any suitably arranged communication system. In thefollowing description, specific details such as detailed configurationand components are merely provided to assist the overall understandingof embodiments of the present invention. In addition, descriptions ofwell-known functions and constructions are omitted for clarity andconciseness.

An embodiment of the present invention provides a blind schedulingapparatus and method in a mobile communication system. In the followingdescription of embodiments of the present invention, the mobilecommunication system is assumed to be a Long Term Evolution (LTE)communication system. However, it will be apparent to those skilled inthe art that the blind scheduling apparatus and method proposed in theembodiments of the present invention may be used other mobilecommunication systems as well as the LTE communication system.

The blind scheduling method proposed in embodiments of the presentinvention may be roughly classified into a first blind schedulingscheme, a second blind scheduling scheme, and a third blind schedulingscheme, each of which will be described below.

In the first blind scheduling scheme, if a User Equipment (UE) beingperiodically allocated a dedicated uplink (UL) resource has no data totransmit on a UL, the UE determines whether to transmit padding MediumAccess Control (MAC) Protocol Data Units (PDUs) according to the type ofthe allocated dedicated UL resource. For convenience, a dedicated ULresource that is periodically allocated to a UE will be referred toherein as a ‘UL grant’.

In the second blind scheduling scheme, when having no data to transmiton a UL, a UE transmits no padding MAC PDU regardless of the type of aUL grant.

In the third blind scheduling scheme, if a UE being allocated a UL granthas no data to transmit on a UL, the UE determines whether to transmitpadding MAC PDUs according to the type of a Cell Radio Network TemporaryIdentifier (C-RNTI).

A process of a UE in an LTE communication system using a first blindscheduling scheme according to an embodiment of the present inventionwill be described with reference to FIG. 1.

FIG. 1 illustrates a process of a UE in an LTE communication systemusing a first blind scheduling scheme according to an embodiment of thepresent invention.

Referring to FIG. 1, the UE detects a type of a UL grant in block 111,and determines in block 113 whether the detected type of the UL grant isan Explicit UL grant. The Explicit UL grant represents a UL grant thatmerely serves as resource allocation information received from anEvolved Universal Terrestrial Radio Access Network (E-UTRAN) Node B(eNB) over a Physical Downlink Control Channel (PDCCH) without separateconfiguration, among UL grants which are allocated after being mapped toa C-RNTI. The Explicit UL grant may also be used to dynamically allocatetransmission resources.

If the detected type of the UL grant is an Explicit UL grant, the UEdetermines in block 115 whether it has data to transmit using theExplicit UL grant. If the UE has no data to transmit using the ExplicitUL grant, the UE ends its process. Specifically, in the conventional LTEcommunication system, even when having no data to transmit using a ULgrant, a UE transmits padding MAC PDUs using the UL grant, therebycausing a waste of UE battery due to the transmission of padding MACPDUs, a signaling overhead due to the exchange of padding MAC PDUs, anda processing load due to the decoding of padding MAC PDUs by an eNB.However, when using the first blind scheduling scheme, the UE transmitsno padding MAC PDUs if it has no data to transmit using the Explicit ULgrant, thereby preventing the above and other problems and disadvantagescaused by the transmission of padding MAC PDUs.

However, if it is determined in block 115 that the UE has data totransmit using the Explicit UL grant, the UE transmits the data usingthe Explicit UL grant in block 117.

If it is determined in block 113 that the detected type of the UL grantis not an Explicit UL grant but a Configured UL grant, the UE proceedsto block 119. The Configured UL grant represents a UL grant that isallocated to a UE that has received a separate SPS configurationInformation Element (IE) such as an SPS C-RNTI. Resource allocationinformation regarding the Configured UL grant is transmitted using aPDCCH, and once allocated, a transmission resource is valid until it isreleased or changed.

In block 119, the UE determines if it has data to transmit using theConfigured UL grant. If the UE has no data to transmit using theConfigured UL grant, the UE transmits padding MAC PDUs using theConfigured UL grant in block 121, and then ends the process.

However, if it is determined in block 119 that the UE has data totransmit using the Configured UL grant, the UE transmits the data usingthe Configured UL grant in block 123, and then ends the process.

In FIG. 1, having data to transmit using an Explicit UL grant and aConfigured UL grant means that transmittable data is present in the datastored in the UE. The data stored in the UE may be classified into datathat can be transmitted and data that should not be transmitted, at anarbitrary time corresponding to a predetermined condition, e.g., aretransmission window status and a transmission window status.

As described with reference to FIG. 1, when having no data to transmiton a UL, the UE determines whether to transmit padding MAC PDUsaccording to the type of a UL grant. If the type of the UL grant is anExplicit UL grant, the UE transmits no padding MAC PDUs when it has nodata to transmit on a UL. A signal exchange process between an eNB and aUE performed in this situation will be described with reference to FIG.2.

FIG. 2 illustrates a signal exchange process between an eNB and a UE inan LTE communication system using the first blind scheduling schemeaccording to an embodiment of the present invention.

Referring to FIG. 2, an eNB 213 sets a value of a New Data Indicator(NDI) for a Hybrid Automatic Retransmission Request (HARQ) process x to‘0’, and allocates an Explicit UL grant for the HARQ process x to a UE211 in an n-th frame in step 215. Here, ‘x’ indicates a unique number ofa HARQ process. In step 217, the UE 211 performs no operation because ithas no data to transmit on a UL in (n+4)-th frame. That is, because thetype of a UL grant is an Explicit UL grant, the UE 211 does not need totransmit padding MAC PDUs when it has no data to transmit on a UL.

Because the eNB 213 has received no data from the UE 211 even though itallocated the Explicit UL grant in the n-th frame, the eNB 213 sets avalue of the NDI to ‘1’ and allocates an Explicit UL grant for the HARQprocess x to the UE 211 in an (n+8)-th frame in step 219. When havingdata to transmit on a UL, the UE 211 transmits the data using theExplicit UL grant in an (n+12)-th frame in step 221.

The eNB 213 decodes the data received from the UE 211 and transmits HARQfeedback information according to the success/failure in decoding. Asfor the HARQ feedback information, a HARQ ACK is transmitted when thedecoding is successful, and a HARQ NACK is transmitted when the decodingis failed. Assuming in FIG. 2 that the eNB 213 has failed to decode thedata received from the UE 211, the eNB 213 transmits a HARQ NACK to theUE 211 in an (n+16)-th frame in step 223. As the UE 211 receives theHARQ NACK from the eNB 213, the UE 211 retransmits the previouslytransmitted data to the eNB 213 in an (n+20)-th frame in step 225.

An operation of the eNB 213 in FIG. 2 will now be described in detailwith reference to FIG. 3.

FIG. 3 illustrates a process of the eNB 213 in FIG. 2.

Referring to FIG. 3, the eNB 213 determines in block 311 whether data isdetected from an allocated Explicit UL grant. If no data is detectedfrom the Explicit UL grant, the eNB 213 proceeds to block 313. Detectingno data from an Explicit UL grant indicates that the UE 211 has nottransmitted data using the Explicit UL grant or the eNB 213 has failedto receive data even though the UE 211 has transmitted the data usingthe Explicit UL grant. Therefore, considering the situation in which theeNB 213 has failed to receive data even though the UE 211 hastransmitted the data using the Explicit UL grant, the eNB 213 sets avalue of an NDI to ‘1’ and allocates an Explicit UL grant to the UE 211in block 313. That is, the eNB 213 may normally operate, even though theUE 211 transmits no padding MAC PDUs as it has no data to transmit on aUL.

However, if it is determined in block 311 that data is detected from theExplicit UL grant, the eNB 213 decodes the detected data in block 315,and determines in block 317 whether it has succeeded in decoding thedetected data. If the eNB 213 has succeeded in decoding the detecteddata, the eNB 213 transmits an HARQ ACK to the UE 211 in block 319.

However, if it is determined in block 317 that the eNB 213 has failed indecoding the detected data, the eNB 213 transmits an HARQ NACK to the UE211 in block 321.

The operation of the eNB 213, described above with reference to FIG. 3,may be performed more effectively when its energy detection reliabilityis relatively high.

Next, an operation of the UE 211 in FIG. 2 will be described in detailwith reference to FIG. 4.

FIG. 4 illustrates a process of the UE 211 in FIG. 2.

Referring to FIG. 4, the UE 211 determines in block 411 whether HARQfeedback information is received from the eNB 213. If no HARQ feedbackinformation is received from the eNB 213, the UE 211 determines in block413 whether it is allocated an Explicit UL grant from the eNB 213. Ifthe UE 211 is allocated an Explicit UL grant, the UE 211 determines inblock 415 whether there is previously transmitted data. If there ispreviously transmitted data, the UE 211 terminates a HARQ process beingperformed on the previously transmitted data in block 417. In block 419,the UE 211 determines if it has data to transmit using the Explicit ULgrant. If the UE 211 has data to transmit using the Explicit UL grant,the UE 211 transmits the data using the Explicit UL grant in block 421.If it is determined in block 415 that there is no previously transmitteddata, the UE 211 proceeds to block 419.

If it is determined in block 411 that HARQ feedback information has beenreceived from the eNB 213, the UE 211 determines in block 423 whetherthere is previously transmitted data. If there is previously transmitteddata, the UE 211 determines in block 425 whether the received HARQfeedback information is a HARQ ACK. If the received HARQ feedbackinformation is not a HARQ ACK but a HARQ NACK, the UE 211 initializes aretransmission process of the HARQ process being performed on thepreviously transmitted data in block 427. However, if it is determinedin block 425 that the received HARQ feedback information is a HARQ ACK,the UE 211 proceeds to block 417.

As described with reference to FIGS. 1 to 4, when allocated an ExplicitUL grant, a UE is allowed not to transmit padding MAC PDUs if it has nodata to transmit on a UL. Even though the UE transmits no padding MACPDUs, the HARQ process between the UE and the eNB may be normallyperformed.

Next, operations of a UE and an eNB in an LTE communication system usingthe second blind scheduling scheme according to an embodiment of thepresent invention will be described.

When the conventional LTE communication system uses SPS, a scheme ofterminating the use of SPS may be roughly classified into two schemes:an implicit scheme and an explicit scheme.

In the implicit scheme, if a UE transmits a padding MAC PDU using aConfigured UL grant a predetermined number of times or more, the UEitself terminates the use of SPS. The information about thepredetermined number of times is included in an SPS configuration IE,and a format of the conventional SPS configuration IE is as shown Table1 below.

TABLE 1 SPS-ConfigUL ::= CHOICE { release NULL, setup SEQUENCE {semiPersistSchedIntervalUL ENUMERATED { sf10, sf20, sf32, sf40, sf64,sf80, sf128, sf160, sf320, sf640, spare6, spare5, spare4, spare3,spare2, spare1}, implicitReleaseAfter ENUMERATED {e2, e3, e4, e8}, ... }}

In Table 1, a semiPersistSchedIntervalUL field represents an intervalfor which a Configured UL grant is allocated, and for example, if avalue of the semiPersistSchedIntervalUL field is ‘sfL’, it indicatesthat a Configured UL grant is allocated every L subframes. Among valuesof the semiPersistSchedIntervalUL field, ‘spareM’ represents a sparevalue of the semiPersistSchedIntervalUL field, which is to be used inthe future. Herein, a value of the semiPersistSchedIntervalUL field thatthe eNB actually transmits in an SPS configuration IE is any one of the‘sfL’ values.

In Table 1, an implicitReleaseAfter field represents the number oftransmissions of a padding MAC PDU which is used to terminate the use ofSPS using the implicit scheme. For example, ‘eN’ indicates that the UEmay terminate the use of SPS after transmitting a padding MAC PDU Ntimes. Herein, a value of the implicitReleaseAfter field that an eNBactually transmits in an SPS configuration IE is any one of the ‘eN’values.

When using the implicit scheme, an eNB terminates the allocation of aConfigured UL grant to a UE if the UE transmits a padding MC PDU as manytimes as the value of the implicitReleaseAfter field. That is, if the UEtransmits a padding MAC PDU as many times as the value of theimplicitReleaseAfter field, both the UE and the eNB no longer use SPS,so they can no longer use the Configured UL grant.

In the second blind scheduling scheme proposed by the present invention,a UE transmits no padding MAC PDUs using a Configured UL grant if it hasno data to transmit using the Configured UL grant. Conventionally, asdescribed with reference to Table 1, when using SPS, if a UE has no datato transmit using a Configured UL grant a predetermined number of timesor more, i.e., the UE transmits a padding MAC PDU a predetermined numberof times or more, the use of SPS is terminated. However, in the secondblind scheduling scheme according to an embodiment of the presentinvention, a modified SPS configuration IE format is proposed such thatthe use of SPS may not be terminated even if a UE has no data totransmit using a Configured UL grant, i.e., if the UE does not transmitdata using the Configured UL grant. The modified SPS configuration IEformat is as shown in Table 2 below.

TABLE 2 SPS-ConfigUL ::= CHOICE { release NULL, setup SEQUENCE {semiPersistSchedIntervalUL ENUMERATED { sf10, sf20, sf32, sf40, sf64,sf80, sf128, sf160. sf320, sf640. spare6, spare5, spare4, spare3,spare2, spare1}, implicitReleaseAfter ENUMERATED {e2, e3, e4, e8, none},... } }

As illustrated in Table 2, while a semiPersistSchedIntervalUL field isthe same as the semiPersistSchedIntervalUL field in the conventional SPSconfiguration IE, an implicitReleaseAfter field is modified to represent‘none’, which indicates that the use of SPS is not terminated even whena UE does not transmit data using a Configured UL grant. Herein, a valueof the implicitReleaseAfter field that an eNB transmits in the modifiedSPS configuration IE is ‘none’.

When using the modified SPS configuration IE, if a UE has no data totransmit on a UL, the use of SPS is not terminated even though the UEdoes not transmit padding MAC PDUs using a Configured UL grant.

In contrast, if a UE transmits as many padding MAC PDUs as a value ofthe implicitReleaseAfter field using a Configured UL grant, an implicitrelease operation of an SPS may be granted to automatically release aConfigured UL grant if the UE does not transmit data during a ConfiguredUL grant occasion corresponding to a value indicated by theimplicitReleaseAfter field, instead of automatically releasing theConfigured UL grant. In this situation, the conventional SPSconfiguration IE format may be used. The Configured UL grant occasionwill be described in detail below.

An SPS grant repeatedly occurs at regular intervals beginning from thetime a Configured UL grant is allocated to a UE over a PDCCH. Forexample, once a Configured UL grant is allocated to a UE at a time ‘x’,the Configured UL grant repeatedly occurs in x+interval, x+2*interval,x+3*interval, and so on, and the UE performs UL transmission using theConfigured UL grants. The time at which the Configured UL grant occursis called a Configured UL grant occasion, and the UE automaticallyreleases the Configured UL grant if the UE does not transmit data usingthe Configured UL grant as it has no data to transmit, during aConfigured UL grant occasion corresponding to the value of theimplicitReleaseAfter field. That is, the UE automatically releases aConfigured UL grant if the UE does not continuously use the ConfiguredUL grant as many times as the value of the implicitReleaseAfter field.The reason for defining the scheme of automatically releasing aConfigured UL grant is to minimize the malfunction problems which mayoccur when a UE mistakes an SPS resource allocated to another UE for anSPS resource allocated to the UE itself because of its failure to detectresidual errors.

Next, operations of a UE and an eNB in an LTE communication system usingthe third blind scheduling scheme according to an embodiment of thepresent invention will be described.

In the third blind scheduling scheme proposed by the present invention,a new C-RNTI is proposed to not allow transmitting padding MAC PDUsusing a UL grant mapped to a pertinent C-RNTI, and the newly proposedC-RNTI will be referred to as Fast Access Scheduling (FAS) C-RNTI. Thatis, a UE may not transmit padding MAC PDUs using a UL grant mapped tothe FAS C-RNTI. An eNB may allocate a FAS C-RNTI to a UE in advance in aprocess before it allocates a UL grant, and a process in which the FASC-RNTI is allocated may be, for example, a Radio Resource Control (RRC)Connection Setup process. It will be apparent to those skilled in theart that the eNB may allocate a FAS C-RNTI to a UE in any process otherthan the RRC Connection Setup process as long as it is a process beforethe eNB allocates a UL grant. For convenience, a scheduling scheme usingthe FAS C-RNTI will be referred to herein as a ‘FAS scheme’.

The eNB may allocate a FAS C-RNTI to UEs when its load is relativelylow. In addition, when there are UEs requiring periodic fast access, theeNB may allocate a FAS C-RNTI to the UEs.

The eNB determines a UL grant mapped to a FAS C-RNTI taking into accountthe Modulation and Coding Scheme (MCS) level, the Transport Block (TB)size, the number of Radio Bearers (RBs), and such. For convenience, a ULgrant mapped to a FAS C-RNTI will be referred to herein as a ‘FASgrant’.

The eNB may inform a UE of an allocation cycle of a FAS grant using aFAS configuration IE and may transmit resource allocation informationfor a FAS grant to a UE using a PDCCH. On the other hand, the eNB maytransmit resource allocation information for a FAS grant to a UE using aPDCCH at any time without using the FAS configuration IE.

The FAS configuration IE is as shown in Table 3.

TABLE 3 FAS-ConfigUL ::= CHOICE { release NULL, setup SEQUENCE {FastAccessSchedIntervalUL ENUMERATED { sf1, sf2, sf5, sf10, sf20, sf32,sf40, sf64, sf80, sf128, sf160, sf320, sf640, spare3, spare2, spare1},... } }

In Table 3, a FastAccessSchedIntervalUL field represents an intervalduring which a FAS grant is allocated. For example, if a value of theFastAccessSchedIntervalUL field is ‘sfL’, it indicates that a FAS grantis allocated every L subframes. Among values of theFastAccessSchedIntervalUL field, ‘spareM’ represents a spare value ofthe FastAccessSchedIntervalUL field, which is to be used in the future.Herein, a value of the FastAccessSchedIntervalUL field that the eNBtransmits in a FAS configuration IE is any one of the ‘sfL’ values.

A process of transmitting a FAS configuration IE to a UE by an eNB willnow be described with reference to FIGS. 5 and 6.

FIG. 5 illustrates an example process of transmitting a FASconfiguration IE to a UE by an eNB in an LTE communication system usinga third blind scheduling scheme according to an embodiment of thepresent invention.

Referring to FIG. 5, a UE 511 transmits an RRC Connection Requestmessage to an eNB 513 in step 515. Upon receiving the RRC ConnectionRequest message, the eNB 513 transmits an RRC Connection Setup messageto the UE 511 in step 517. The RRC Connection Setup message includes aFAS C-RNTI allocated to the UE 511, and a FAS configuration IE(represented by ‘FAS-Config’ in FIG. 5).

Upon receiving the RRC Connection Setup message, the UE 511 transmits aRRC Connection Setup Complete message to the eNB 513 in step 519. Whenthe RRC Connection Setup process between the UE 511 and the eNB 513 iscompleted, the eNB 513 allocates a FAS grant to the UE 511 and transmitsresource allocation information for the FAS grant to the UE 511 througha PDCCH (FAS grant on DPCCH) in step 521.

FIG. 6 illustrates another example process of transmitting a FASconfiguration IE to a UE by an eNB in an LTE communication system usinga third blind scheduling scheme according to an embodiment of thepresent invention.

Referring to FIG. 6, an eNB 613 transmits an RRC ConnectionReconfiguration message to a UE 611 in step 615. The RRC ConnectionReconfiguration message includes a FAS configuration IE (represented by‘FAS-Config’ in FIG. 6).

Upon receiving the RRC Connection Reconfiguration message, the UE 611transmits an RRC Connection Reconfiguration Complete message to the eNB613 in step 617. When the RRC Connection Reconfiguration process betweenthe UE 611 and the eNB 613 is completed, the eNB 613 allocates a FASgrant to the UE 611, and transmits resource allocation information forthe FAS grant to the UE 611 through a PDCCH (FAS grant on DPCCH) in step619.

A process of a UE in an LTE communication system using a third blindscheduling scheme according to an embodiment of the present inventionwill now be described with reference to FIG. 7.

FIG. 7 illustrates a process of a UE in an LTE communication systemusing a third blind scheduling scheme according to an embodiment of thepresent invention.

Referring to FIG. 7, the UE detects a type of a UL grant in block 711,and determines in block 713 whether the detected type of the UL grant isa FAS grant. If the detected type of the UL grant is not a FAS grant,the UE performs an operation corresponding to the detected type of theUL grant in block 715.

However, if it is determined in block 713 that the detected type of theUL grant is a FAS grant, the UE determines in block 717 whether it hasdata to transmit using the FAS grant. If the UE has no data to transmitusing the FAS grant, the UE no ends the process. That is, as describedabove, the UE may not transmit padding MAC PDUs using the FAS grant.

However, if it is determined in block 717 that the UE has data totransmit using the FAS grant, the UE transmits the data using the FASgrant in block 719.

As described with reference to FIG. 7, if the type of the UL grant is aFAS grant, the UE transmits no padding MAC PDUs when it has no data totransmit on a UL. A signal exchange process between an eNB and a UEperformed in this situation will be described with reference to FIG. 8.

FIG. 8 illustrates a signal exchange process between an eNB and a UE inan LTE communication system using a third blind scheduling schemeaccording to an embodiment of the present invention.

The signal exchange process between an eNB and a UE illustrated in FIG.8 is substantially the same as that described with reference to FIG. 2except that the UL grant replaces a FAS grant, so a detailed descriptionthereof will be omitted.

A process of the eNB 813 in FIG. 8 will be described in detail withreference to FIG. 9.

FIG. 9 illustrates a process of the eNB 813 in FIG. 8.

The process of the eNB 813 illustrated in FIG. 9 is substantially thesame as that described with reference to FIG. 3 except that the UL grantreplaces a FAS grant, so a detailed description thereof will be omittedherein. Likewise, the process of the eNB 813, illustrated in FIG. 9, maybe performed more effectively when its energy detection reliability isrelatively high.

Next, a process of the UE 811 in FIG. 8 will be described in detail withreference to FIG. 10.

FIG. 10 illustrates a process of the UE 811 in FIG. 8.

The process of the UE 811 illustrated in FIG. 10 is substantially thesame as that described with reference to FIG. 4 except that the UL grantreplaces a FAS grant, so a detailed description thereof will be omittedherein.

As described with reference to FIGS. 7 to 10, when allocated a FASgrant, the UE is not allowed to transmit padding MAC PDUs even though ithas no data to transmit on a UL. Even though the UE transmits no paddingMAC PDUs, the HARQ process between the UE and the eNB may be performednormally.

Next, an internal structure of an eNB in an LTE communication systemaccording to an embodiment of the present invention will be describedwith reference to FIG. 11.

FIG. 11 illustrates an internal structure of an eNB in an LTEcommunication system according to an embodiment of the presentinvention.

Referring to FIG. 11, the eNB includes a control unit 1111, a resourceallocation unit 1113, a transmission unit 1115, and a reception unit1117.

The control unit 1111 controls the overall operation of the eNB toperform operations corresponding to the first to third blind schedulingschemes proposed by the present invention. These operationscorresponding to the first to third blind scheduling schemes andperformed by the eNB have been described above, so detailed descriptionsthereof will be omitted herein.

The resource allocation unit 1113 allocates resources or UL grants undercontrol of the control unit 1111, and a type of a UL grant allocated bythe resource allocation unit 1113 is determined according to the firstto third blind scheduling schemes, as described above.

The transmission unit 1115 transmits resource allocation information fora UL grant allocated by the resource allocation unit 1113 under controlof the control unit 1111. The transmission unit 1115, under control ofthe control unit 1111, transmits HARQ feedback information for the datareceived through the reception unit 1117, and transmits a controlmessage such as an RRC Connection Setup message. The resource allocationinformation and control messages transmitted by the transmission unit1115 have been described together with the first to third blindscheduling schemes, so detailed descriptions thereof will be omittedherein.

The reception unit 1117, under control of the control unit 1111,receives data from a UL grant and decodes the received data. Thereception unit 1117 receives control messages such as an RRC ConnectionRequest message, and the control messages received through the receptionunit 1117 have been described together with the first to third blindscheduling schemes, so detailed descriptions thereof will be omittedherein.

Next, an internal structure of a UE in an LTE communication systemaccording to an embodiment of the present invention will be describedwith reference to FIG. 12.

FIG. 12 illustrates an internal structure of a UE in an LTEcommunication system according to an embodiment of the presentinvention.

Referring to FIG. 12, the UE includes a control unit 1211, atransmission unit 1213, and a reception unit 1215.

The control unit 1211 controls the overall operation of the UE toperform operations corresponding to the first to third blind schedulingschemes proposed by the present invention. These operationscorresponding to the first to third blind scheduling schemes andperformed by the UE have been described above, so detailed descriptionsthereof will be omitted herein.

The transmission unit 1213 transmits data using a UL grant allocatedfrom an eNB under control of the control unit 1211. The transmissionunit 1213 transmits control messages such as an RRC Connection Requestmessage under control of the control unit 1211. The control messagestransmitted by the transmission unit 1213 have been described togetherwith the first to third blind scheduling schemes, so detaileddescriptions thereof will be omitted herein.

The reception unit 1215 receives HARQ feedback information and controlmessages such as RRC Connection Setup messages from an eNB, undercontrol of the control unit 1211. The control messages received throughthe reception unit 1215 have been described together with the first tothird blind scheduling schemes, so detailed descriptions thereof will beomitted herein.

As is apparent from the forgoing description, the present inventionenables blind scheduling that prevents unnecessary transmission ofpadding MAC PDUs, thereby minimizing a waste of the UE battery due tothe transmission of padding MAC PDUs, minimizing a signaling overheadcaused by the exchange of padding MAC PDUs, and minimizing a processingload due to the decoding of padding MAC PDUs by an eNB.

Although the present disclosure has been described with an exemplaryembodiment, various changes and modifications may be suggested to oneskilled in the art. It is intended that the present disclosure encompasssuch changes and modifications as fall within the scope of the appendedclaims.

What is claimed is:
 1. A method of a terminal in a communication system,the method comprising: receiving a radio resource control (RRC) messagerelated to a first uplink (UL) grant; identifying the first UL grantbased on the RRC message; identifying that there is no data to transmitbased on a first UL resource related to the identified first UL grant;and determining not to generate a medium access control (MAC) protocoldata unit (PDU) to transmit, based on the identified first UL grant andthe identification that there is no data to transmit based on the firstUL resource, wherein the RRC message includes a first identifier (ID) ofthe terminal and a period of the identified first UL grant, and theidentified first UL grant is associated with the first ID of theterminal.
 2. The method of claim 1, wherein the MAC PDU is a padding MACPDU.
 3. The method of claim 1, further comprising: receiving informationrelated to a second UL grant on a physical downlink control channel(PDCCH); identifying the second UL grant based on the receivedinformation; identifying that there is no data to transmit based on asecond UL resource related to the identified second UL grant; anddetermining to generate the MAC PDU to transmit, based on the identifiedsecond UL grant and the identification that there is no data to transmitbased on the second UL resource.
 4. The method of claim 3, wherein theidentified second UL grant is associated with a second ID of theterminal.
 5. A terminal in a communication system, comprising: atransceiver; and at least one processor configured to: control thetransceiver to receive a radio resource control (RRC) message related toa first uplink (UL) grant, identify the first UL grant based on the RRCmessage, identifying that there is no data to transmit based on a firstUL resource related to the identified first UL grant, and determine notto generate a medium access control (MAC) protocol data unit (PDU) totransmit, based on the identified first UL grant and the identificationthat there is no data to transmit based on the first UL resource,wherein the RRC message includes a first identifier (ID) of the terminaland a period of the identified first UL grant, and the identified firstUL grant is associated with the first ID of the terminal.
 6. Theterminal of claim 5, wherein the MAC PDU is a padding MAC PDU.
 7. Theterminal of claim 5, wherein the at least one processor is furtherconfigured to: control the transceiver to receive information related toa second UL grant on a physical downlink control channel (PDCCH),identify the second UL grant based on the received information, identifythat there is no data to transmit based on a second UL resource relatedto the identified second UL grant, and determine to generate the MAC PDUto transmit, based on the identified second UL grant and theidentification that there is no data to transmit based on the second ULresource.
 8. The terminal of claim 7, wherein the identified second ULgrant is associated with the second ID of the terminal.
 9. A method ofbase station (BS) in a communication system, the method comprising:generating a radio resource control (RRC) message related to a firstuplink (UL) grant; and transmitting the RRC message to a terminal,wherein a medium access control (MAC) protocol data unit (PDU) is notgenerated by the terminal, based on the first UL grant identified basedon the RRC message and identification that there is no data to transmitbased on a first UL resource related to the first UL grant, and whereinthe RRC message includes a first identifier (ID) of the terminal and aperiod of the first UL grant, and the first UL grant is associated withthe first ID of the terminal.
 10. The method of claim 9, wherein the MACPDU is a padding MAC PDU.
 11. The method of claim 9, further comprising:transmitting, to the terminal, information related to a second UL granton a physical downlink control channel (PDCCH), wherein the MAC PDU isgenerated by the terminal, based on the second UL grant identified basedon the transmitted information and the identification that there is nodata to transmit based on a second UL resource related to the second ULgrant.
 12. The method of claim 11, wherein the second UL grant isassociated with a second ID of the terminal.
 13. A base station in acommunication system, comprising: a transceiver; and at least oneprocessor configured to: generate a radio resource control (RRC) messagerelated to a first uplink (UL) grant, and control the transceiver totransmit the RRC message to a terminal, wherein a medium access control(MAC) protocol data unit (PDU) is not generated by the terminal, basedon the first UL grant identified based on the RRC message andidentification that there is no data to transmit based on a first ULresource related to the first UL grant, and wherein the RRC messageincludes a first identifier (ID) of the terminal and a period of thefirst UL grant, and the first UL grant is associated with the first IDof the terminal.
 14. The BS of claim 13, wherein the MAC PDU is apadding MAC PDU.
 15. The BS of claim 13, wherein the at least oneprocessor is further configured to control the transceiver to transmit,to the terminal, information related to a second UL grant on a physicaldownlink control channel (PDCCH), and wherein the MAC PDU is generatedby the terminal, based on the second UL grant identified based on thetransmitted information and the identification that there is no data totransmit based on a second UL resource related to the second UL grant.16. The BS of claim 15, wherein the second UL grant is associated with asecond ID of the terminal.